package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private static final ExecutorService seckill_order_executor = Executors.newSingleThreadExecutor();
    @PostConstruct
    private void init(){
        seckill_order_executor.submit(new VoucherOrderHandler());
    }

    String queueName = "stream.orders";
    private class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            int a = 0;
            while (a == 1){
                try {
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 count 1 BLOCK 2000 STREAMS streams.order >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2.判断消息获取是否成功
                    if (list == null || list.isEmpty()){
                        // 2.1如果获取失败, 说明没有消息, 继续下一次循环
                        continue;
                    }
                    // 3.解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    // 4.如果获取成功, 可以下单
                    createVoucherOrder(voucherOrder);
                    // 5.ACK确认 SACK stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();
                }
            }
        }
    }

    private void handlePendingList() {
        int a = 0;
        while (a == 1){
            try {
                // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 count 1 STREAMS streams.order 0
                List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                        Consumer.from("g1", "c1"),
                        StreamReadOptions.empty().count(1),
                        StreamOffset.create(queueName, ReadOffset.from("0"))
                );
                // 2.判断消息获取是否成功
                if (list == null || list.isEmpty()){
                    // 2.1如果获取失败, 说明pending-list没有异常消息, 结束循环
                    break;
                }
                // 3.解析消息中的订单信息
                MapRecord<String, Object, Object> record = list.get(0);
                Map<Object, Object> values = record.getValue();
                VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                // 4.如果获取成功, 可以下单
                handleVoucherOrder(voucherOrder);
                // 5.ACK确认 SACK stream.orders g1 id
                stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
            } catch (Exception e) {
                log.error("处理pending-list订单异常", e);
                try {
                    Thread.sleep(20);
                } catch (InterruptedException ex) {
                    ex.printStackTrace();
                }
            }
        }
    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        // 1. 获取用户
        Long userId = voucherOrder.getUserId();
        // 2. 创建锁对象
        RLock redisLock = redissonClient.getLock("lock:order:" + userId);
        // 3. 获取锁
        boolean isLock = redisLock.tryLock();
        //4. 判断是否获取锁成功
        if (!isLock){
            //获取锁失败, 返回错误或重试
            log.error("不允许重复下单");
            return;
        }
        try {
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            // 释放锁
            redisLock.unlock();
        }
    }

    private IVoucherOrderService proxy;

    @Override
    public Result seckillVoucher(Long voucherId) {
        // 获取用户
        Long userId = UserHolder.getUser().getId();
        // 获取订单id
        Long orderId = redisIdWorker.nextId("order");
        // 1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(), String.valueOf(orderId)
        );
        // 2.判断结果是否为0
        int r = result.intValue();
        if (r != 0){
            // 2.1.不为0, 代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        // 4.返回订单id
        return Result.ok(orderId);
    }

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //5.一人一单
        Long userId = voucherOrder.getUserId();
        //6.1查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        //6.2判断是否存在
        if (count > 0) {
            //用户已经购买过了
            log.error("用户已经购买过一次!");
            return;
        }
        //5.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")  //set stock = stock - 1
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0) //where id = ? and stock > 0 ?
                .update();
        if (!success) {
            //扣减失败
            log.error("库存不足!");
            return;
        }
        save(voucherOrder);
    }
}
